Electric safety fuse



July `1 7, 1923 1,462,013

s. J. KNUDsx-:N

ELECTRIC SAFETY FUSE Filed April 30. 1921- /ffarny Patented July 17, 1923.

l UNITED STATES SVEND JOHANNES KNUDSEN, OF COPENHAGEN. DENMARK.

ELECTRIC SAFETY FUSE.

Application filed April 30, 1921. Serial No. 11G-5,665,

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. L., 1313.)

T all whom it may concern:

y Be it known that I, SvnND JOHANNES KNUDSEN, a subject of the King; of Denmark, residing at 11 Langogade, Copenhagen, Denmark, have invented certain new and useful Improvements in Electric Safety Fuses (for which I have tiled applications in Denmark` lVlarch 8, 1919; Sweden, November 17, 1919; England, December 6, 1919; Norway, January 8, 1920; and Germany,

December 29, 1919) of which the following is a specification.

This invention relates to electric safety fuses.

AccordingJ to this invention the fuse comprises a top member with fuse wires inserted in holes therein which are parallel with the axis of said member and a bottom member carrying the bottom contact and the contact sleeve ofthe fuse and being rotatably connected to the top member by means of an axial bolt rigidly kconnected to the bottom contact. The invention is charac- 'terised-bythe fact that the fuse wires extend from said holes over the top face of the top member Adown into a central cavity in the same to a disc seated therein and connected to all the fuse wires and to the bottom contact, the axial bolt or spindle being rigidly connected to a cover arranged over the top face of the top member and adapted to'be turned together with the bottom member.'

The invention will now be described more fully with reference to the accompanying,r drawings which represent one embodiment thereof.' In these drawings Figure 1 is a longitudinal section of the improved safety fuse.

Figure 2 is a plan of the same with the cover removed.

Figure 3 is a bottom view of lthe top member of the fuse.

The fuse consists of the top member 1 wherein all of the fuse wires 2 are inserted and fastened separately and the bott-om member 3 connected rotatably to the top member and supporting the terminals of the fuse viz., the bottom contact 4. and a threaded contact-sleeve 5. The top and bottom members are held together axially under resilient pressure exerted by a helical spring 6 which is inserted in a central cavity 7 in the top member and which acts on the bottom member to draw it towards the top member. The bottom member 3 is connected rotatably to the top member 1 by means of a cent-ral spindle 8 which passes through the latter and is firmly secured to the bottom member 3 as by being clinched thereto and the bottom contact 4 inserted therein and which is firmly connected, on the end of the top member farthest away from the bottom member, to a cover 9 for the top member. On the end of the top member which faces the bottom member there are inserted, in a circular row of holes, a number of metal plugs or studs 10 corresponding to the number of fuse wires; the said studs, as shown, projecting slightly beyond the bottom face of the top member and each being' connected with the end of one of the fuse wires 2 of the safety fuse. On the end facing the top' member` the bottom member 3 is provided with a contact member 12 having' a terminal 13 which hooks over the said face of the bottom member and is sunlr into the side of the bottom member, inside the contact-sleeve 5 and held in position by the latter. By soldering the contact-piece 12 and the contact-sleeve 5 together. anv casual rota-tion of the latter relatively to the bottom member is prevented. rfhe contact 13 rests against the end of one of the met-al studs 10. the fuse wire of which is in circuit for the time being. By rotation of the top member relatively to the bottom member, the contact 13 may be caused to touch any one of the metal studs 10, and the contact-sleeve 5 may thus be connected to any one of the fuse wires. These wires are of inverted U-shape, as shown, and their outer branches extend each from one of the studs 10, up through a circular row of axially directed holes 14 in the top member, to the upper end of said member and then radially or laterally inward. their inner branches extending downwardly to one and the same disc 16 disposed on the bottom wall of the central cavity 7 in the top member, all of the fuse wires being connected to this disc. The disc 16 is connected electrically to the spindle 8 by means of the spring 6, the latter being compressed between the disc 16 and a nut 15 of conductive material rmly screwed on the spindle.

,any suitable number of fuse wires.

The helical spring 6 exerts an upwardly directed pressure on the nut 1 5,this pres sure being transmitted by the spindle 8 to the bottom member 3 which is thereby forced against thev bottom face of the top member 1 with a suitable degree of pressure. A lining 17 of mica or other suitable insulating material may be inserted in the cavity 7 so as to insulate the fuse wires from the spring 6. The cover 9 encircles the upper edge of the top member 1 and is formed with a number of holes 19 which correspond to the number of fuse wires and are disposed immediately above these wires so that all of the fuse wires are visible. Otherwise the' cover is fastened to the top end of the spindle 8 in any suitable manner, for instance by means of cement, litharge or the like'.

The end of the top member which faces the bottom member is formed with a number of teeth 20 corresponding to the number of fuse wires, one side of these teeth being sloping and the other side vertical, and the teeth 20 engaging other teeth 21 on the correspondingly toothed top face of the bottom member 3. The teeth 20 and 21 are disposed in such a manner relatively to the holes 10 and the contact 13 on the bottom member that a proper position of one of the metal plugs 10 relative to the vcontact 13 is securedy every time the teeth of the upper and lowery member enter into engagement, after a rotary displacement (corresponding to the spacing of the teeth) of the upper member relative to the bottom member.

When a fuse wire is fused, or when for some other reason a fuse wire has to be replaced, the' top -member has to be turned .6 Will then force the top member down against the bottom member, and the last mentioned metal plug Will thereby be caused to touch the contact 13.

c The safety fuse may be constructed with The metal plugs 10 may be hollow or solid, and may be fastened to the top member in any suitable manner. Instead of a series of teeth 20 on the upper member, a single tooth may Lof course be used which may be caused to engage any tooth space in a series of teeth 21 on the bottom member, or vice versa.

Inorder to ascertain which fuse wire is in circuit at a given moment7 the holes 19 in the cover 9 may be so disposed that one -of said holes comes directly above the contact 13, and this hole or its circumference may be provided With a special mark.

Havingnow particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. A multiple-fuse plug, comprising a top member provided with a central cavity and with an annular series of vertical fuse holes encircling the same and opening at their opposite ends through the corresponding end faces of said member; a series of contact studs on the inner end of said member at the inner ends of said holes; a disc' in said cavity; a plurality of bent fuse-wires having their inner branches disposedI in said cavity and connected at their free ends to said disc and their outer branches disposed in said holes and connected at their freev ends to said studs, the Central portions of said Wires Vextending laterally across thel outer end face of said member; a bottom member; a spindle passing axially through the top and bottom members to connect them together and to which said top and bottom members are rotatably and rigidly related, respectively; a contact sleeve on the bottom member having an extension to interchangeably engage said studs; and coacting sets of teeth on` the confronting inner ends of said members having inclined faces for sliding engagement with each other during the rotation of the top member relative to the bottom member, said teeth being so disposed with relation to he contactv studs that one stud will beheld in correct contact position whenever the sets of teeth come into full engagement.

A multiple-fuse plug, comprising ai top member provided with a central cavity and with an annular series of vertical fuse holes encircling the same and opening at their opposite ends through the corresponding end faces of said member; a series of contact studs on the inner end of said member at the inner ends of said holes; a disc in said cavity; a plurality of bent fuse-wires having their inner branches disposed in said cavity and connected at their free endsV to said disc and their outer branches disposed in said holes and connected at their free ends to said studs, the central portions of said wires extending laterally acrossl the outer end face of said member; a bottom member; a spindle passing axially through the top and bottom members to connect them together and to which said top and bottom members are rotatably and rigidly related, respectively; a cover for theI top member rigidly secured to the outer end of said spindle, saidl cover and top member being rotatably related; a contact sleeve on the bottom member having an extension to interchangeably engage said studs; and coacting sets of teeth on the confronting inner ends of said members having inclined lfaces for sliding engagement With each other during the rotation of the top member relative to the bottom member, said teeth being so disposed with relation to the Contact studs that one stud will be held in correct contact position Whenever the sets of teeth come into full engagement.

3. A multiple-fuse plug, comprising top and bottom members; a spindle connecting said top and bottom members and on which they are rotatably and rigidly mounted9 respectively; a series of fuse Wires carried by the top member and electrically connected at one end with said spindle, each Wire having a portion thereof extending laterally across the outer end face of the top member.; a series of contact studs, one ttor each use Wire, disposed against the inner end 'tace of the top member and to which the wires are connected at their other end; contact element on the bottom member having a portion for interchangeable engagement with said studs; and a cover for the top member, and to which that member is rotatably related, fixed to the upper end ci the spindle so as to permanently occupy the same position with relation to the bottom member` said cover having an opening in line with the stud-engaging portion oi` the contact elen ment on the bottom member' so as to expose the laterally-extending portion ot the particular fuse Wire which is electrically connected With said studengaging portion through the corresponding Contact stud any given time.

4i. A multiple-fuse plug7 comprisine' -ng top and bottom members; a spindle connecting said top and bottom members and on which they are rotatably and rigidly mounted1 respectively; a series of fuse Wires carried by the top member and electrically connected at one end With said spindle, each wire having a portion thereof extending laterally across the outer end tace oiy the top member; a series of contact studs, one for each fuse Wire7 disposed against the inner end 'face of 'the top member and to which the Wires are connected at their other end; a contact element on the bottom member having a. portion for interchangeable engagement with said studs; sets ot coacting teeth on lthe confronting inner ends oit the top and bottom members having inclined faces Jtor sliding engagement with each other during the rotationV of the top member relative to the bottom member, said teeth being so disposed with relation to the contact studs that one stud Will be held in correct contact position vwhenever the sets ot teeth come into full engagement; and a cover for the top member, and to which that member is rotatably related7 lined to the upper end of the. spindle so as permanently occupy the same position with relation to the bottom member, said cover having an opening in line With the stud-engaging portion of the contact element on the bottom member so as 'to expose the laterally-extending portion of the pard ticnlar inse Wire which is electrically connected `with said stud-engaging portion through the corresponding contact stud at any given time.

in testimony Whereo;Ic I ailix my signature.

SVEND JOHANNES KNUDSEN. lVitnesses:

CARL AIEMMINGEN, ULLA BANG. 

